The invention relates to a vehicle roof with a sliding roof element disposed in a roof opening which is delimited by a guide frame in which the sliding roof element is movable by an operating mechanism between a closed position and an open position in which the sliding roof element is disposed below a rear section of the vehicle roof.
DE OS 26 58 018 discloses a roof element in a vehicle roof opening which is movably supported in a frame delimiting the roof opening so as to adjustable between a closed position in which the roof opening is closed by the roof element and an open position in which the roof element extends over the surface of the roof. The transfer between the closed and the open positions occurs by an operating mechanism including levers hinged to the roof element and comprising a front lever which is engaged in a front guide track and a rear lever, which is engaged in a rear guide track mounted to the vehicle body. The two guide tracks are arranged longitudinally one after the other, within a guide structure. The two guide tracks extend each horizontally in the guide structure and facilitate lifting of the roof element at the front end thereof or at the rear end thereof or concurrent lifting of the front and rear ends of the roof element.
Such roof elements are used particularly in buses. They are generally not used in passenger cars since, with the high travel speeds of passenger cars, a lifting of the front end of the roof element is not possible because of the high wind resistance.
A similar vehicle roof is described in the publication DE 196 35 145 C1, which discloses also a guide bar structure with two guide bars which are disposed behind one another and which consist each of a plurality of sections with different inclinations alternating with horizontal sections. This arrangement provides for intermediate resting position of the roof element between the closed and the maximum open positions. The transfer to the open position, or respectively, the various intermediate positions is achieved by means of a drive carriage, which is movably supported by the guide frame and which engages the guide track by way of guide pins. Depending on the actual position of the drive carriage, guide pins are disposed in different sections of the guide tracks and thereby guide the roof element to the various positions.
Neither of the two references discloses a sliding roof element that can be moved below the plane of the roof and under a roof section adjacent the roof opening. The printed publication EP 648 624 B1 discloses a sliding roof with a roof element which, in the open position, is moved below a roof section behind the roof opening. The guide mechanism operating the roof element however is not disclosed in this publication.
The printed publication DE 84 35 809 U1 discloses a vehicle roof with a slidable roof element disposed in a vehicle roof opening which can be moved during transition from a closed to an open position in a combined longitudinal and vertical motion under a rear part of the vehicle roof. The operating mechanism providing for the movement of the roof element comprises two separate tracks, which are arranged one after the other in the longitudinal direction of the vehicle, and into each of which a guide pin extends. The two guide tracks have vertical inclinations and are disposed at different height levels wherein the rear guide track has a greater inclination and also a greater height difference between the front end and the rear end thereof. The shapes of the guide tracks need to be adapted to each other since otherwise the guide pins might lock in the guide tracks. As a result, the design freedom of this structure is limited.
For general technological background information reference is further made to the publications DE 3 616 176 A1 and DE 40 06 160 C2.
Based on this state of the art, it is the object of the invention to provide a vehicle roof with a roof opening and a movable roof element, which is disposed in the roof opening and which, during movement from a closed to an open position, can, with simple means, be lowered and moved below a roof section disposed behind the roof opening with only little intrusion into the vehicle interior.
In a vehicle roof with a roof opening and a sliding roof element movable between a closed position in which the roof element is disposed in the roof opening and an open position in which the roof element is moved below a section of the vehicle roof behind the roof opening, wherein the roof opening is delimited by a guide frame provided with a guide track structure including front and rear guide track channels into which guide pins of the roof element project, the guide track channels for the two guide pins have front sections with inclinations which are greater for the rear guide pin than for the front guide pin so that the rear end of the roof element is lowered faster during initial opening movement than the front end of the roof element and the guide pins are so mounted on the roof element as to be able to accommodate different distance requirements during transition of the roof element between the open and the closed positions.
During movement from the closed to the open position, the roof element is lowered below the section of the roof behind the roof opening in a combined vertical and longitudinal movement. The transfer movement is performed in such a way that, in the first phase of the movement, the front end and the rear end of the roof element are lowered vertically to a different degree whereby a diving motion of the roof element below the rear roof section is achieved. This has the advantage that the headroom of the front seat occupants is intruded as little as possible since, first the rear end of the roof element is lowered below the roof and the front end of the roof element is lowered vertically only during a later transfer phase. This diving motion of the roof element is achieved in that the front guide track has a smaller inclination than the rear guide track. The inclination or gradient is measured over the vehicle length, wherein a lower inclination of the front track with regard to the rear track provides for a lowering of the front end of the roof element over a distance in the direction of the longitudinal vehicle axis then for the rear end of the sliding roof element. The different inclinations or gradients also provide for a faster lowering of the rear end of the sliding roof element than for the front end of the sliding roof element at a given speed of movement along the longitudinal vehicle axis. Vice versa, the raising speed for the rear end of the roof element is greater than the raising speed of the front end of the roof element at the end of the closing movement of the sliding roof element. As a result, the head room of the front seat occupants is only little intruded by the sliding roof element during the opening and closing procedure.
At least one of the two guide pins extending into the guide tracks is supported on a length compensation element which provides for a length compensation for the respective pin with respect to the other during the transfer movement from the closed to the open position or vice versa. A length compensation may become necessary if the front and rear guide tracks include section with substantially different curvatures whereby during the various movement phases of the roof element different distances between the two guide pins are necessary. The length compensation element provides for such distance compensation between the two guide track pins.
The length compensation element is provided preferably in the form a slide slot in which a guide track member is disposed which is firmly connected to the guide pin.
Preferably, the front guide track consists of three sections of which the center section extends horizontally so that when the respective guide pin is received in this center section of the front guide track the roof element is not raised or lowered but performs only a horizontal sliding movement. Adjacent the horizontal center track section of the front guide track, there are end sections extending forwardly and rearwardly which are inclined in such a way that the front end section of the front guide track overcomes a smaller height difference than a front section of the rear guide track.
In this way, the front end of the roof element is lowered at the beginning of the opening movement only by a smaller amount than the rear end of the roof element during the same horizontal movement phase. With the different amount of lowering of the front end of the roof element with respect to the rear end thereof, the roof element is inclined in such a way that the front end which is disposed over the heads of the front seat occupants leaves sufficient head room for the occupants of the front seats.
When the front part has completed the vertical movement during the first phase of an opening movement of the roof element in accordance with the front section of the guide track a horizontal movement follows in the next phase of movement in accordance with the horizontal center section. In the last phase of movement, the front part of the roof element is further lowered in accordance with the rear inclined section of the front guide track down to a level, which permits sliding of the roof element below the rear roof section.
In a preferred embodiment of the invention, at least one of the two guide tracks, preferably however both guide tracks includes a parallel extending additional guide track section into which a positioning bolt extends. The additional guide track and the positioning bolt provide for a minimum engagement of the roof element in the guide tracks at opposite sides whereby any play between the guide track pins and the respective guide tracks can be eliminated and the roof element can be moved in a play- and noise-free manner. In addition, the additional guide tracks and the positioning bolts disposed therein can support the movement of the guide track pins particularly in curved sections or in transition areas between two guide track sections so as to avoid locking and cogging.
Below, an embodiment of the invention will be described in greater detail on the basis of the accompanying drawings.